Re: [PATCH] dma-mapping: Stub out dma_{alloc,free,map}_pages() API

[Christoph Hellwig]

On Mon, Jun 16, 2025 at 01:06:00PM +0100, Mark Brown wrote:
> On Mon, Jun 16, 2025 at 01:29:27PM +0200, Christoph Hellwig wrote:
> > On Mon, Jun 16, 2025 at 12:17:49PM +0100, James Clark wrote:
> 
> > > The implementations are in mapping.c which requires HAS_DMA so stub them
> > > out if not present. This is required for some drivers to pass randconfig
> > > builds.
> 
> > No.  Just add the proper IS_ENABLED checks in the callers.  While these
> > kinds of stubs used to be popular they are really nasty in that the
> > calls unexpectedly just fail without the right depends.
> 
> The issue with HAS_DMA is that essentially all platforms have and rely
> on DMA.  This ends up just being painful noise from the buildbots when
> they do randconfigs rather than something useful.

In most case the driver really does depend on DMA to work, so just
depend on HAS_DMA.  If it can work without DMA, you can use IS_ENABLED.